I. Field of the Invention
This invention is related to scaffolds or work platforms and, more particularly, is directed towards a scaffold which may be used in conjunction with a forklift truck.
II. Description of Related Art
The prior art is replete with structures which set forth various schemes for manipulating a work platform or scaffold, some in conjunction with a forklift truck or other prime mover. By and large, these schemes are complex, subject to mechanical and/or electrical breakdowns, and too expensive. Following is a brief discussion of a representative sample of prior art United States patents in this area.
Crow (U.S. Pat. No. 668,627) shows a scaffold in which movement of the platform relative to the base is effected by means of a worm gear "k" which is hand-cranked by the person on the scaffold.
Clement et al. (U.S. Pat. No. 2,413,909) disclose in FIG. 1 a linesman's platform 56 cantilevered from a support tower 27. Platform 56 is rotatable about tower 57 by means of a workman-operated hand-crank and gear 58 coacting with a crowngear 59 to position the platform anywhere in a 360 degree circle.
Campbell et al. (U.S. Pat No. 2,966,956) show a platform 21 which is moved about by means of forks 36 of a forklift truck being inserted into loops 51.
Mitchell (U.S. Pat. No. 3,509,965) provides a platform 16 which is vertically moveable on a multi-sectioned, telescoping mast 14 that is horizontally extendable relative to the mast from a centered position to a cantilevered position (cf. FIGS. 1 and 2) and appears rotatable through 360 degrees by means of a turntable 12 (column 6, lines 31-36).
Cullity (U.S. Pat. No. 4,271,926) provides a work platform 22 rotatable about a boom connection 24 through 180 degrees by means of a pair of hydraulic cylinders 52 and 60.
Rybka, deceased (U.S. Pat. No. 4,936,414) attaches a scaffolding platform 40 to an extendable boom 38 which, in turn, is attached to a turret 22 rotatably mounted on a rigid base 30. Tine-receiving sockets 100 on base 30 permit the assembly to be lifted and moved by a forklift truck 24.
Freywiss (U.S. Pat. No. 5,078,021) shows the use of a worm gear and a toothed gear to effect relative rotary motion between a laterally extending motor 26 and a vertical shaft
Pierce (U.S. Pat. No. 5,088,577) discloses a framework attachable to a scaffolding and used to lift and move the scaffolding. Sleeves 12 receive the tines 14 of a forklift truck which lifts and moves the assembly.
Dickenson, Jr. (U.S. Pat. No. 5,096,018) lifts and positions a manbasket by means of a forklift truck.
As noted above, most of the foregoing structures are needlessly complicated, have too many moving parts, are subject to electrical and/or mechanical breakdown, and are simply too expensive to be used on a wide scale. It would therefore be highly desirable if there could be provided a work platform or scaffold which could be used with an ordinary forklift truck, which is rotatable 360 degrees, and which would be inexpensive, easy to use, and reliable in operation. It is towards these ends that the present invention is advanced.